Weather Activity: Exploring Evaporation and Condensation by Making it Rain

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Spring has arrived, and with it comes rain showers!

Rain is a form of precipitation that’s released from the clouds through a process called the water cycle. It helps to replenish groundwater and surface water, which provide drinking water for most of the world’s population.

It’s formed when the sun heats water on the earth’s surface - like oceans, lakes and rivers - and turns it into water vapor through evaporation. The water vapor rises into the air, cools and creates liquid-forming clouds through condensation. Once the clouds become full, the water falls back to the earth in the form of rain, snow or hail.

To further explain how rain is formed, watch this video that teaches kids about the water cycle in a fun way.

You can also show students first-hand how rain is formed. The experiment below illustrates that when warm, moist air meets cold air, the moisture in the warm air condenses and falls out.

Fill the mason jar three-fourths of the way with hot water and screw the metal lid on. Cover the lid with the plate and let it sit for a few minutes while the water warms up the air inside.

Have students place ice cubes onto the plate.

Watch as the cold plate cools the air inside the jar, making condensation run down the sides of the jar.

Take the experiment further to show how rain comes from clouds.

Instructions:

Get a cup of water and mix in blue food coloring.

Instead of placing the lid and a plate of ice on the top of your mason jar, make a sort of cloud out of shaving cream on top of a jar completely filled with room-temperature water.

Using a pipette, drop colored water into the shaving cream cloud. When it gets too full, the colored water will drop down into the jar and you’ll see rain coming through!

Science Behind the Experiment:

Condensation: When you add hot water to the mason jar and cap it, some of the water evaporates into the air inside. When that air meets the cold plate at the top, the water droplets in the air condense and fall down the side of the jar like rain.

Evaporation: Clouds are formed from condensed water (from the first part of the experiment). When those condensed water droplets become too heavy, “rain” falls from the shaving cream clouds.